1. Field of the Invention
The present invention relates to an electrical apparatus with juxtaposable modules which can be electrically connected to one another by bridge elements. More particularly, the present invention relates to providing reliable connections between juxtaposable modules and bridge elements using at least recesses with insertable sleeves and interposing sealing gaskets.
2. Description of the Related Technology
Prior Art apparatuses, as are known for example from DE 297 03 367 U1 are often used as subscriber devices in bus systems for control and monitoring of technical processes using sensors and actuators that can be connected to the modules via apparatus connectors.
To seal the connecting site between the bridge elements and the modules, in the prior art the interfitting parts are made interlocking. One such version however, due to the required production precision, dictates high production costs. Nevertheless the attainable sealing effect is poor. To improve it, therefore in the known apparatus there is an additional seal, for example, a flat seal, as is used in the apparatus known from DE 296 07 525 U1, which when the bridge elements are inserted into the modules in the insertion direction, are pressed against the bottom part of blind recesses which is used as a contact carrier in the module housing. To produce the pressure required for this purpose, in the known apparatus, there are threaded screws which are pushed through the holes of the bridge elements and can be screwed into threaded holes in the modular housing. Without this screw attachment the bridge elements, especially when these apparatuses are used on machines, would not be positionally stable and the contact-making of the connectors would not be resistant to vibrations.
The object of the invention is to devise an electrical device of the initially mentioned type in which the connections for the bridge elements and the modules have a permenance which meets high requirements (degree of protection IP 67) in a simple and economical manner, and the disconnection force is as high as possible and vibration-resistant, and the interconnection of the connectors is ensured without additional fasteners.
This object is achieved by using at least recesses with insertable sleeves and interposing sealing gaskets.
By use of a cylindrical shape for penetrations, both economical and effective O-shaped gaskets, e.g. rings, can be used as the sealing devices; the O-shaped gaskets achieve their sealing force which acts essentially in the radial direction at a constant distance from the contact surfaces solely by their dimensions and material properties and do not require any additional features, such as more compression, or contact surfaces such as abutments. Moreover, the O-shaped gaskets can be very easily installed by being slipped onto the outside sleeves surrounding connectors or the mating connectors and do not need to be inserted into a blind recess or into grooves at the bottom part of blind recesses, as in the apparatus known from DE 297 03 367 U1.
In addition, the penetrations can be produced much more economically than blind recesses. Bur mainly the penetrations and the pertinent contact carriers can be located on separate parts of the electrical apparatus; this greatly simplifies both production and installation and enables versatile use. The penetrations are made either in the module housings or in the bridge elements, the pertinent contact carriers thereby independently can be included for example on circuit boards within the modules or bridge elements.
Furthermore, the outside sleeves which bear the O-shaped gasket are not form-fitted to the walls of the penetrations either, by which production is greatly simplified and more economical.
The compressing force of the gasket for appropriate selection and dimensioning of the distances of the contact surfaces is so great that forces for insertion and extraction of up to 10 kg are reached and thus in general no special additional features are necessary for sealing the attachment of the bridge elements. This has the advantage not only of a significant reduction in production and installation costs, but also easier handling, since the bridge elements, for example for replacement of modules in case of servicing, can be slipped on and withdrawn by hand.
By having an insertable outside sleeve integral with the bridge unit or the module housing, without additional sealing features, ensures tightness also at the insertion sites of the outside sleeve into the respective penetration.
By incorporation of an oblique arrangement of the contact surfaces for the O-shaped gasket, without any additional costs an increase of the insertion and withdrawal forces up to roughly 15 kg which is independent of the O-shaped gasket composition and the relevant dimensions can be achieved, because the compression force of the gasket that is directed perpendicular to the contact surfaces includes a force component arising from insertion due to the tilt of the contact surfaces. As a result of this increased withdrawal force on the one hand and the vibration-damping action of the elastic gasket on the other the resulting electrical apparatus is suited for mounting on the mounting surfaces of highly vibrating machines without additional fastening devices.
One version of the module housing that provides structural dimensions comparable to those of the bridge element and also includes plug-and-socket connections on the module housing for actuators, sensors and a field bus enables a very compact apparatus with a low structural height which can also be used in many applications where there is little space available for installation.
By way of a partition extending from the module housing with a crosspiece, provides, if necessary, support for the bridge elements slight tilting which is possible in extreme cases or in case of unintentional bumping so that for these cases reliable sealing and a high withdrawal force are achieved. The dimensions are chosen such that the cited compactness of the module housing is preserved. This embodiment can be accomplished essentially without additional costs by one-piece production.
Another very simple and feasible embodiment of the apparatus of the present invention, has T-shaped projections and corresponding guide slots extend from the module housing so that the modules can be attached to one another by hand (and if necessary can be detached from one another). Exact guidance of the projections into the slots moreover ensures that the center distances of the modules adjacent to the mating connectors facing one another always corresponds exactly to that of the connectors of the bridge elements, by which exactly centered axial insertion of the connectors into the penetrations and thus optimum sealing and retaining action are ensured.
A console-shaped execution of the module housing has the advantage that the labeling fields and display elements positioned on the oblique console surfaces are easily visible in the arrangement on or under roughly horizontal surfaces but also in a wall mounting. This is the more so when all labeling fields and display elements are located on the tilted console surface.
In another version of the module housing there are mounting feet extending from the module for resting on an installation surface. Between the housing bottom and the mounting surface there is a gap through which air flows (convection flow) which advantageously dissipates the lost heat released from the encapsulated modules. Compared to the prior art according to German utility models 296 07 525 and 297 03 367 in which the modules are located without spacing on the mounting sheets, the operating temperature for the present invention is lower and thus the service life of the modules is increased.
It is especially economical to produce the feet in one piece with the module housing, for example in an injection molding process, and to provide them at the same time with holes for screw attachment of the modules to mounting surfaces.
The convection flow between the housing bottom and the mounting surface and thus also the heat dissipation are especially strong when the housing bottom is made trough-shaped and to taper toward housing end faces.
A further intensification of cooling of the modules can be achieved incorporating elevations (domes) as part of the housing bottom in that housing bottom has a surface as large as possible for heat dissipation, for which especially tubular domes are suited for the elevations (domes). The cross sections of the domes can be made in any shape, for example, square or round.
A grid-like arrangement of these domes, by which corridors which run in the flow direction between the domes are formed, moreover facilitating the dissipation of unwanted lost heat.
A one-piece execution of the domes and housing bottom not only reduces production costs, but also ensures optimum heat transfer from the housing bottom to the dome surfaces.
Overall, a noticeable prolongation of the apparatus service life is achieved by incorporation at lease these features of mounting feet, housing bottom spaced from mounting surfaces, and elevations (domes) integrated as part of housing bottoms.
It is a good idea to use a circuit board for internal line connections and to accommodate electrical switching elements, which the board can be attached in the module housing very easily and economically by a press fit.
Depending on the separation of the assigned mating connectors from their penetrations, the connectors can be mounted on the circuit board and in doing so their contact elements can be connected directly to the pertinent printed conductors of the circuit board without additional connecting lines.
In one advantageous embodiment of the bridge elements a connector to feed an operating voltage independent of the bus lines into the modules is enabled. Conductor cross sections can thus be adapted to [the] feed currents which are desired in the individual case. For example, they can be designed for currents so high that a plurality of sensors and especially actuators can be supplied. This is not possible in the transmission of operating voltages via bus lines, for which reason for example in the apparatus known from DE 296 07 525 U1 requires an additional feed module ASI. When using bridge elements according to this embodiment of the present the invention, no such device is necessary.
In many applications, for individual actuators and groups of actuators separate operating voltage circuits are desired, for example when the operating voltage for certain actuators in case of a hazard is to be disconnectible on an emergency basis without influencing the remaining subscribers over the bus line. This is enabled by formation of the bridge elements by having only one conductor for the operating voltage, which bridge elements are inserted on the pertinent modules simply and economically. With these bridge elements, flexible adaptation to the different requirements of the individual case is thus achieved with respect to the operating voltage supply. Conversely, in the known apparatuses only a supply of all actuators and sensors is possible.